More than 90 per cent of frontline officers had never done mental health training, despite being called out to suicides, threats of self-harm and violent incidents of so-called ''death by cop''.

In 2013, NSW Police responded to 43,830 mental health related incidents, up from 38,524 in 2012. The number of incidents could reach 50,000 this year, police say.

The introduction of a one-day training course comes a week after mentally ill Greg Anderson killed his son, Luke Batty, 11, in Victoria.

From Monday, two teams will begin teaching a mental health intervention course, with the aim of reaching every officer in NSW.

NSW Police spokesman for mental health, Superintendent David Donohue, said Luke's tragic death showed how important it is for police to better understand mental health.

''That father suffered mental illness. It rang true to what we are trying to get to; not saying that training would change the outcome but that death by cop is a reality and it's becoming more prevalent in the US. How do you manage that?''

Superintendent Donohue said he was in the witness box during an inquest into a fatal police shooting when he came to the realisation that all officers needed training.

''It's [mental health incidents] the most prevalent I've seen in 25 years. Not a shift goes by where police don't deal with something that is mental health related.''

Two coroners had asked him why there was not training for every policeman and he realised there was a major gap.

For the past four years, Superintendent Donohue encouraged the commander of the mental health intervention team, Inspector Joel Murchie, to develop the course, with the help of NSW Health.

Inspector Murchie said four officers and two mental health nurses would train 13,500 officers in the next three years. Once the roving training is completed, the program will switch to the NSW Police Academy in Goulburn, so all recruits are trained.

Superintendent Donohue said the course would teach officers about common mental illnesses and show them ways to identify certain conditions ''because sometimes we don't know if [a person] is drug-affected or, in some instances, the person might be suffering from a brain injury'', he said.

Coronial findings in cases in which police have killed mentally ill people would be discussed and officers would have the chance to participate in mock scenarios.

Inspector Murchie said the rising number of mental health related incidents was a concern but said there many reasons for it.

Better police awareness meant officers were more likely to ''tag'' jobs as mental health related.

The increased prevalence of illicit drug use and the stresses of modern life were also likely to increase the number of incidents, he said.

NSW Police's mental health intervention team was made a permanent unit in 2009.